Don't laugh, first try at pixel animation..

[Cluey]

Small is powerful...

[HillBilly]

If the gun is meant to be powerful, I suggest it backfires more.

[Nexic]

I like it!

[Flippy_D]

Yeah, you want more punch.

Have the arms and gun go back, and if you're feeling confident, have the gun tip point upwards, trailing plasma. That'll make it look ridiculously powerful... if done right.

[Penguinx]

Example of extreme kickback.

[Damien]

Very nice sprite and animation Cluey.

I'm not sure if your gif program is causing this, but there are too many colors for a sprite of such small size.

[Al_Ninio]

His arms should also be more stretched out.
Aiming, or just shooting a gun this size without breaking your own shoulder with the arms in this position, would be impossible.
Nice sprite overall, though.

[Shane 'ProgZmax' Stevens]

Very impressive, Cluey.  I would suggest that you not show the actual result of the firing, since you're looking for a big bang type deal (and would never see the projectile anyway).  Try a muzzle flash instead, and more kickback like others have suggested.

I made a quick edit, but to really improve the muzzle flash you could add a range of orange to red hues to your palette.  When the guy fires you will notice that the barrel lights up, this can be extended to the character as well.

[InCreator]

I like it!

I'd still go for some kind of projectile, just a cooler one.
Something like this...